The present invention relates generally to handled utility tools and, more specifically, to a tire bead breaking wedge and method for the use thereof.
Tire bead breaking wedges are known in the art and are in commercial use. Such tools generally comprise an elongate handle affixed at one end to a wedge head. The wedge head comprises an elongate body, typically formed from cast metal, having a striking surface at one end and a wedge edge at an opposite end. A circular cross-sectional through-bore extends through the tool head at a location representing the center of mass.
The handle for the subject type of tool is generally of elongate, cylindrical configuration extending from a gripping end to an inverted frustro-conical forward end. The handle may be of wood, metal, plastic, or a composite composition. The forward end of the handle may further be coated with a rubber or other high coefficient of friction material.
Assembly of the wedge head to the handle is achieved by inserting the handle gripping end downward through the head bore until the forward end of the handle enters the bore of the head. The dimension of the forward end of the frustro-conical handle portion is oversized relative to the head bore. Accordingly, driving the frustro-conical handle portion downward into the bore of the head wedges the forward portion of the handle into the bore and establishes a tight, frictional press fit connection between the handle and wedge head.
In use, the user positions the working edge of the tool between a wheel rim and tire bead. Thereafter, a hammer is applied to the striking surface, serving to drive the wedge edge downward and thereby forcing the wedge edge against an underedge of the wheel rim. Using the wheel rim as a fulcrum, the handle is rotated and causes the wedge arm to impinge against the tire bead and force the bead downward. The downward pressure of the wedge arm upon the tire bead is continued until the bead of the tire is depressed a sufficient distance so as to disengage from the wheel rim. Should the bead prove resistant, a user of the bead-breaking wedge will typically pry the wedge head back and forth until engagement between the bead and the wheel rim is broken. Subsequent thereto, the wedge arm is extracted from between the tire bead and the wheel rim. Such extraction can prove difficult and require prying the wedge back and forth to effectuate its disengagement.
A bead breaking wedge of the aforementioned type is commercially sold as a Model 35329 wedge and T11E head by Ken-Tool Company, of 768 E. North Street, Akron, Ohio 44305. While the implement works well and has met with considerable commercial success, it has been found that rocking the wedge back and forth against the tire bead can, over time, cause the handle forward end portion to work its way loose from the wedge head, requiring a re-tightening by the user. Still further, repeated rocking action of the wedge head relative to the handle may act to frictionally wear away the portions of the inverted frustro-conical handle end lying along the wedge head longitudinal axis until only the lateral sides of the forward handle end remain in frictional engagement with the wedge head. In this condition, the wedge head may become free to rock backward and forward about the lateral sides of the forward handle end, xe2x80x9cplayxe2x80x9d that is undesirable to the intended purpose of the tool. Eventually, the head will become loose from the handle and a retightening will be required. However, once the handle forward portion becomes worn to a considerable degree, a re-tightening of the handle to the tool head in known tools becomes increasingly problematic.
In order to postpone, if not eliminate, loosening between the handle forward end and the wedge head, handle manufacturers have incorporated ribs along the inverted frustro-conical outer surface of the forward handle end. The ribs engage circular sidewalls defining the wedge head bore. As the tool is used, the ribs wear away at a slower pace and a positive frictional engagement between the head and the handle is prolonged. The ribs, however, are of narrow width dimension making the area of surface to surface contact between the handle end and the wedge head less than desired. In addition, though occurring at a slower pace, the ribs will eventually wear away. When the ribs are gone, the handle and wedge head will loosen in the manner described above. A repeated retightening of the wedge head connection with the handle will be increasingly required and over time, re-tightening, as explained above, becomes increasingly problematic.
A second deficiency in known handles for tire bead breaking wedges is that it is common for a user to inadvertently contact the wheel rim with a portion of the tool during the tire bead breaking procedure. Such repeat contact can, in time, cause a structural failure of the handle proximate the wedge head. In addition, the handle gripping area in known tools is generally smooth and regular. Establishing and maintaining a tight grip upon the tool handle can become increasingly difficult as the user becomes fatigued.
Yet a further deficiency is that a considerable amount of force is generally required to force the tire bead downward a distance sufficient to disengage from the wheel rim. Since the wedge contacts the tire bead at only one point of contact, i.e. the working end of the wedge arm, all of the requisite downward force is concentrated upon only one area of the tire bead. The magnitude of force necessary to deflect one area of the tire bead downward a sufficient distance is greater than optimally desired. In addition, impinging upon the tire bead with a relatively large force at only one point of engagement can damage the tire bead. Still further, once the tire bead is disengaged from the wheel rim, the wedge working edge typically sticks between the tire bead and the wheel rim. Dislodging the wedge edge from its position between the rim and the bead requires considerable prying, an arduous effort that slows the process and fatigues the user of the tool.
Accordingly, there is a need for a tire bead-breaking tool having a head to handle frictional connection that will not degrade or become disconnected from repeated use of the tool over time. Moreover, the wedge head should provide means for efficiently depressing the tire bead downward during the bead breaking procedure, requiring a minimal amount of force. Still further the force required to break the bead should be applied in such a manner as not to damage the tire. Finally, the wedge head should facilitate a ready extraction of the wedge edge from between the rim and the tire bead once the bead breaking procedure is complete with a minimal amount of prying required.
It is, therefore, an object of the invention to provide a handle for a utility tool that establishes and maintains a positive frictional engagement with the tool head.
A further object is to provide a tire bead breaking wedge that requires a minimal level of efficiently applied force to depress the tire bead a sufficient distance from the wheel rim so as to disengage.
Yet a further object is to provide a tire bead breaking wedge that minimizes damage to the tire bead during the tire bead breaking procedure.
Another object of the invention is to provide a tire bead breaking wedge that facilitates a ready extraction of the wedge lever arm from between the tire bead and the wheel rim once the procedure is finished.
A further object of the invention is to provide a tire bead breaking wedge that provides a positive and efficient application of mechanical advantage through the wedge arm to the tire bead.
Additionally, it is an object of the invention to provide a method for efficiently and safely separating a tire bead from a wheel rim with minimal risk of damage to the tire.
A further object is to provide a tire bead breaking wedge that is economically and readily manufactured.
The aforementioned objectives, and other objectives that will be apparent to one skilled in the art, are achieved by a tool described and claimed below. The handle comprises an elongate gripping portion stepping at a forward shoulder to a shield portion having a thicker dimension than the gripping portion. An inverted frustro-conical handle working portion is connected to a forward end of the shield portion and is configured oblong in cross-section having protruding opposite end surfaces and substantially less protruding lateral surfaces disposed between the end surfaces.
The working portion of the handle wedges within an oval in cross-section through-bore of a wedge head and establishes positive frictional engagement between the protruding surfaces and tool head bore sidewalls. The protruding surfaces align and face along the longitudinal plane of the wedge head and use of the tool serves to drive the protruding surfaces into the bore, whereby reinforcing the frictional connection between the handle and the tool head. Less protruding lateral sides of the handle working end are separated from the sides of the tool head bore by gaps avoid contact therewith.
The wedge head comprises an elongate arm extending to a forward terminal wedge edge. A bead breaking protrusion is positioned offset a rearward distance from the wedge edge and projects outward from the wedge arm. The protrusion comprises a beveled leading edge and a beveled trailing edge intersecting at a rounded edge. The method of utilizing the tool includes inserting the wedge edge between the tire bead and wheel rim, and driving the wedge arm edge against a free edge of the wheel rim. The wedge arm is thereafter driven downward a second distance until the wedge arm protrusion engages an inboard portion of the tire bead. Thereafter, using the wheel rim as a fulcrum, the wedge arm is rotated downward by the handle and first and second points of engagement are established against the tire bead by the wedge arm and the arm protrusion, respectively. Continuing to leverage the wedge arm against an underside of an edge of the wheel rim, the wedge arm is rotated a further distance downward, pressuring the tire bead downward at the first and second areas of engagement, until separation of the tire bead from the wheel rim is complete.
The invention as summarized above is described in detail below and illustrated by the accompanying drawings.